Efficacy of three 15N labelling techniques for estimating below-ground N in Sesbania rostrata

Abstract.

Three 15N labelling strategies for estimating below-ground N in Sesbania rostrata grown in pots under flooded conditions were examined. The estimated proportions of total plant N resident below-ground were 13% (stem injection), 42% (leaf immersion) and 56% (adventitious root feeding). The average estimate based on leaf and root immersion (49%) was considered to be realistic on the basis of published literature with other foliar labelled legumes, while root and root-derived N appeared to be underestimated by stem injection.